Half to frederick a



(N0 Mbdel.)

H. B. RIEH LE. WEDGE GLAMP.

Patented Nov. 8,1881.

UNITED STATES PATENT OFFICE;

HENRY B. RIEHLE, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR OF ONE- HALF TOFREDERICK A. RIEHLE, OF SAME PLACE.

WEDGE-CLAMP.-

- SPECIFICATION forming part of Letters Patent No. 249,259, datedNovember 8, 1881.

Applicrtion filed May 20, 1881. (No model.)

To all gvhom it may concern:

Be it known that I, HENRY B. RIEHLE, of Philadelphia, in the county ofPhiladelphia and State of Pennsylvania, have invented a 5 new and usefulimprovement in a wedge of peculiar shape, to be used in holdingboiler-plate or flat specimens in a testing-machine, or be applied forother purposes to resist a strain, of which the following is aspecification.

The object of my invention is to obtain a perfectly central pull orstress on flat material without the possibility of tearing from thesides or edges, a difficulty heretofore existing in wedge-gripesgenerally.

My invention consists of a wedge havingits cut face which gripes thespecimen slightly raised through its center longitudinally its entire orpartiallength. The center line can be approached either by a curve or ina straight 2o manner.

I am aware that wedges with curved backs, and wedge seatsor lilies withbacks or faces arched are made to accommodate specimens of uneventhickness. They, nevertheless, will p not prevent'a twist or torsion ifopposite corners of specimens above and below are unequal in thicknessor the surfaces are harder, or it teeth of wedges are worn awayunevenly, allowing slipping or shifting of the specimen also. In myimproved wedge the specimen is engaged at once through the axial line,and presses continuously a little harder at the center (throughout theentire test) than it does on the edges. The edgesarethusrelievedunderall circumstances, and a side pull causing a tear 5 is impossible,and anydanger from a twist prevented. I do hereby declare that thefollowing is a clear, full, and exact description thereof, referencebeing had to the accompanying drawings, in which similar letters andfigures 40 indicate like parts.

Figure 1 is a plan view of an ordinary specimen holder or clamp. Fig. 2is a vertical sectional view, and Fig. 3 is a modification of thewedge-face.

The clamp A-is held in position in the machine by the bolts B B.

In Figs. 1,2,and 30 0 represent the wedges. In Fig. l the faces ofwedgesG G, which press against the specimen D, are curved, while in Fig. 3 thefaces are straight to the center line. Both are shown more curved orinclined than in reality.

The letters e on Figs. 1 and 2 represent a steel pin held by aset-screw, which acts as a guidein upper and lower clamp, to brin gspecimens to the center perpendicularly.

What I claim as my invention is- A wedge adapted to hold flat bars in atestingmachine, having its vise or biting-face 6o throughoutits entirelength, or a portion th ereof, raised in a central longitudinal line,substantiall y as described, and for the purpose set forth.

HENRY B. RIEHLE.

Witnesses:

CHARLES RoBsoN, WILLIAM F. HOGAN.

